It is known that the action of insecticides decreases over time due to resistance phenomena of the insects on account of their developed ability to strengthen their natural defences. A solution to the problem of resistance consists of increasing the dosage of the insecticide so as to restore the action itself; however, this solution is negative in two aspects linked to the increased resistance induced and to the environmental pollution resulting from the high dosages used. Another possible solution is linked to the rotation of insecticides with the same mechanism of action, but with the risk of seeing the development of cross-resistance phenomena.
There have therefore been proposed substances, which by acting on the enzyme systems of the insects, can restore the sensitivity to insecticides, by reducing or eliminating the resistance phenomena and are furthermore capable to increase the sensitivity of the insects themselves even in the case in which there are no resistance phenomena thus contributing to, in any case, lowering the doses of the insecticides used. These products are known as synergists and include derivatives of 1,3-benzodioxole, in particular piperonyl butoxide (also known as PBO),

5-[2-(2-butoxyethoxy)-ethoxymethyl]6-propyl-1,3-benzodioxole, is known to be a powerful synergist for insecticides, in particular in respect of pyrethrins, pyrethroids, insect growth regulators (IGR), carbamates, organic phosphorus compounds and, recently, also neonicotinoids and other insecticides such as, for example, those of the METI (Mitochondrial electron transport inhibitors) class.
In order to further and significantly improve the insecticidal action of the final formulations, above all for use in the presence of resistance phenomena, there have also been proposed formulations of insecticides and piperonyl butoxide both as complexes in cyclodextrins and microencapsulated in microcapsules made of polymer material. For this latter formulation, the piperonyl butoxide acts immediately on the enzyme systems of the insects, restoring the sensitivity thereof so that the insecticide released after some time may carry exercise its action.
In view of the synergistic action of the piperonyl butoxide there were proposed derivatives of the 1,3-benzodioxole as alternative products for the synergistic action in the insecticidal compositions.
In U.S. Pat. No. 7,354,911 there are described derivative compounds of 1,3-benzodioxole of formula

Wherein R1 is an alkyl group or a C3 alkenyl group and R2 is a C1-C3 alkyl group. In WO 2011/020848 compounds of formula (I) are described:

Among the various meanings of R1, R2 and R3, there is highlighted the fact that R1O— and R2O— taken together can represent a —O—CH2—O— group or a benzodioxole group and that R3 is a (C1-C6)alkyl and y is 0, 1 or 2. These compounds are proposed as synergists of insecticidal active ingredients, in particular of the class of pyrethroids.
It is still felt the need to provide additional synergistic products to be employed with insecticidal active ingredients.